Our overall aim is to carry out the biochemical characterization of the molecular constituents of the mammalian spermatozoon, particularly those components that are important for the architectural integrity of this highly differentiated cell and that relate to its functions in fertilization. We combine biochemical procedures with electron microscopic examinations to investigate the effects of various treatments on spermatozoan structure and function. We have developed several chemical dissection procedures for spermatozoa from five mammalian species and purified subcellular fractions have been obtained in quantities sufficient for biochemical analysis. Separated heads, and intact tails, sperm without mitochondria, and tails without mitochondria can be produced by chemical treatment. We will extend these methods and analyze the distribution of molecular components within these fractions. The regional specialization of the spermatozoan membrane will be investigated using lectins and antibodies as specific probes to map the sperm surface. The in vitro fertilization assay will also be used to analyze the effects of various treatments of spermatozoa in order to define more precisely the molecular components of sperm responsible for their interaction with the egg and for fertilization.